(a) Field of the Invention
This invention relates to a push-pull amplifier, and more particularly to a biasing arrangement for a direct-coupled push-pull amplifier employing Field Effect Transistors.
(b) Description of the Prior Art
A conventional output transformerless (OTL) amplifier has such advantage as to need no output transformer which may cause wave distortion, unfavorable frequency characteristic, and power loss. However, most of the recent solid-state OTL amplifiers employing a single ended push-pull (SEPP) circuit need a coupling capacitor which shows a higher impedance in lower band. Therefore, these amplifiers have unfavorable frequency characteristic in lower band.
An output capacitorless (OCL) amplifier is free from the disadvantages described above.
There is a known OCL amplifier with direct-coupled stages supplied by center grounded negative and positive batteries. But, if all stages are composed of Field Effect Transistors (FET), the bias circuit would be complicated because of the batteries which must be provided independently for each amplifier stage.